Research On Sound Absorption Characteristics Of Hemispherical Cavity Film Composite Structure

Noise in industrial environment is one of common pollution.For example,in a stamp forming workshop,the stamping process usually causes rapid air compression and produces impulse noises,which far exceeds the normal hearing limit of ordinary people.Otherwise,that is extremely harmful to the human body.At present,workers wear sound insulation earmuffs,but it is adverse to communication,and the huge cost of establishing an anechoic chamber in a factory.On the one hand,the stamping process will inevitably produce high-intensity noise that cannot be easily eliminated;on the other hand,an effective isolation technology is urgently warranted.The refore,it is necessary to develop sound insulation technology.A novel composite structure of hemispherical cavity with thin film and viscous fluid(CSHCFF)was proposed,in order to reduce the impact noise effectively.The main research work of this paper is as follows:(1)Firstly,the theoretical model of CSHCFF was established.The acoustic coupling modes of CSHCFF were calculated,and the regularities of the numbered order vibration modes were analyzed,which explores the impact of the coupling effect of the viscous fluid and the film.And the high fidelity simulation model about measurement of SAC is established.Based on the theory and simulation model,the CSHCFF was manufactured.(2)In this research subject,a series of experimental specimens were designed,which explained the process of energy dissipation.Parametric analysis of CSHCFF has implemented,including volume ratio of viscous liquid to the cavity,the thickness of the thin film,viscous liquid concentration,hemispheric cavity radius an d contact form of thin film and viscous fluid.The theoretical explanations are obtained in engineering,otherwise sound absorption design methods are provided.(3)Based on the results of parametric analysis,the acoustic shield of CSHCFF has developed,exploring preliminarily for practical engineering application.The CSHCFF are found to significantly improve sound shielding,which proves that the CSHCFF has a potential application prospect in sound isolation and absorption engineering.In the sum,the research is helpful to comprehensively understand the acoustic characteristics of CSHCFF,and provides n ovel design ways for practical engineering.